Horton

Re: [PoC] pg_upgrade: allow to upgrade publisher node

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: "Hayato Kuroda (Fujitsu)" <kuroda.hayato@fujitsu.com>
Cc: Peter Smith <smithpb2250@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Bruce Momjian <bruce@momjian.us>, Julien Rouhaud <rjuju123@gmail.com>, vignesh C <vignesh21@gmail.com>, Masahiko Sawada <sawada.mshk@gmail.com>, "Zhijie Hou (Fujitsu)" <houzj.fnst@fujitsu.com>
Date: 2023-08-22T06:48:15Z
Lists: pgsql-hackers 
On Mon, Aug 21, 2023 at 6:32 PM Hayato Kuroda (Fujitsu)
<kuroda.hayato@fujitsu.com> wrote:
>
> > 2.
> > + /*
> > + * Checking for logical slots must be done before
> > + * check_new_cluster_is_empty() because the slot_arr attribute of the
> > + * new_cluster will be checked in that function.
> > + */
> > + if (count_logical_slots(&old_cluster))
> > + {
> > + get_logical_slot_infos(&new_cluster, false);
> > + check_for_logical_replication_slots(&new_cluster);
> > + }
> > +
> >   check_new_cluster_is_empty();
> >
> > Can't we simplify this checking by simply querying
> > pg_replication_slots for any usable slot something similar to what we
> > are doing in check_for_prepared_transactions()? We can add this check
> > in the function check_for_logical_replication_slots().
>
> Some checks were included to check_for_logical_replication_slots(), and
> get_logical_slot_infos() for new_cluster was removed as you said.
>

+ res = executeQueryOrDie(conn, "SELECT slot_name "
+   "FROM pg_catalog.pg_replication_slots "
+   "WHERE slot_type = 'logical' AND "
+   "temporary IS FALSE;");
+
+ if (PQntuples(res))
+ pg_fatal("New cluster must not have logical replication slot, but
found \"%s\"",
+ PQgetvalue(res, 0, 0));
+
+ PQclear(res);
+
+ nslots = count_logical_slots(&old_cluster);
+
+ /*
+ * Do additional checks when the logical replication slots have on the old
+ * cluster.
+ */
+ if (nslots)

Shouldn't these checks be reversed? I mean it would be better to test
the presence of slots on the new cluster if there is any slot present
on the old cluster.

-- 
With Regards,
Amit Kapila.

Commits

  1. Fix issues in binary_upgrade_logical_slot_has_caught_up().

  2. Fix a random failure in 003_logical_slots.pl.

  3. Fix a test in 003_logical_slots.

  4. Fix uninitialized slot array access during the upgrade.

  5. Fix the test 003_logical_slots.

  6. Commit b195e6d482 forgot to update meson.build.

  7. Use shorter file names in the upgrade logical slots test.

  8. Migrate logical slots to the new node during an upgrade.

  9. Flush logical slots to disk during a shutdown checkpoint if required.

  10. Prevent possibility of panics during shutdown checkpoint.